IMMOBILIZATION PROCEDURES AT MARBURG PARTICLE THERAPY CENTER, MARBURG, GERMANY

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1 Project co-funded by the European Commission within the FP7 ( ) ULICE Union of Light Centres in Europe Page 1 of 8

2 IMMOBILIZATION PROCEDURES AT MARBURG PARTICLE THERAPY CENTER, MARBURG, GERMANY Authors: Andrea Wittig 1, Urszula Jelen 1, Rita Engenhart-Cabillic 1, Jean Michel Moreau 2, Guillaume Vogin 2, Jacques Balosso 3, Pascal Pommier 3, Marie-Helene Baron 3 1 Philipps-University Marburg, Germany; 2 UCBL: Université Claude Bernard Lyon, France; 3 ETOILE: Espace de Traitement Oncologique par Ions Legers Europeen European Light Ion Oncological Treatment Centre, France Name of the institution: Partikel Therapy Zentrum Marburg Country: GERMANY 1 the survey Immobilization devices (ID) ensure a reproducible irradiation during the treatment course. They aim to reduce the treatment setup errors and intra/inter fractional tumor motion ( CTV to PTV margins) WITHOUT interfering significantly with the beam s characteristics. The following survey aims to intercompare the practices in terms of immobilization between the existing or planed particle radiotherapy facilities within Europe. ID have to be mentioned in any clinical protocol in order to interpret the results. Uniformized practices may help to reduce methodological biases in the coming multicentric trials. 1. Technical issues 1.1 What kind of immobilization devices (ID) do (will/would) you use? homemade x manufactured: which company/brand? Macromedics, CIVCO 1.2 Are (will/would they be) they? standardized x customized If you answered «customized», 1.3 Who is in charge of the preparation of the ID? the radiation oncologist the physicist a dedicated immobilization specialist Page 2 of 8

3 - x a radiation therapist / technologist, ( + ID checked by radiation oncologist) a radiation dosimetrist 1.4 How long does it take to manufacture any ID for any adult patient? minutes 1.5 When does it take place in the treatment process? x prior to the planning CT at the same time as the planning CT 1.6 Do (will/would) you use any of these ID? Bite block yes x no Thermoplastic mesh mask (aquaplast ) and other holders yes x no (but solid rather than mesh mask) Vacuum bags yes x no Body fix (hip fix) yes x no Plastic casting holders (eg. body thermoplastic mask) yes x no Stereotactic head frame yes no x Alpha cradle rising foam yes no x Moldcare yes no x Page 3 of 8

4 Any other common ID: 1.7 What kind of material would you recommend? carbon fiber acrylic polyurethane other: No specific recommendation 2. Physical issues 2.1 Did (will/would) you modelize its attenuation in your TPS? yes x no (only Hounsfield numbers) 2.2 Did (will/would) you pay attention to its chemical composition? yes x no 2.3 Is (will/would) the incident ion beam going (go) through the ID mater? (but sharp edges in the field will be avoided) If you answered «yes», 2.4 Do (will/would) you take it into account for the dosimetry? How? - Stopping power calculated based on CT HU values. yes x no 2.5 Due to the particular interactions taking place into the ID, shall (should) it give rise to any specific radioprotection issue (activation, neutron emission, dose increase to the skin, etc)? If «yes», precise: Page 4 of 8

5 3. Economical issues 3.1 Did (will/would) you pay attention to its cost? 3.2 Could you give an estimation of the ID cost per patient? Euro 4. Accuracy issues 4.1 Did (will/would) you pay attention to its accuracy? 4.2 How do (will/would) you check the accuracy of your ID / repositioning? x daily imaging (X-ray or portal or Cone-Beam) Orthogonal X-Ray and automatic image matching. weekly imaging (X-ray or portal or Cone-Beam) x In-situ CT scan X In-situ PET imaging 4.3 Do (will/would) you use a robotic treatment table? 5. Pediatric specificities 5.1 Do (will/would) you use specific ID for children 5.2 If yes, which one(s)? yes x no 5.3 Would you recommend beams traversing the anesthesia mask in H&N, CNS or skull base locations? Page 5 of 8

6 6. Miscellaneous 6.1 Do (will/would) you train the radiation therapist to the proper use of the ID? 6.2 Where do (will/would) you store the ID? dedicated storage space 6.3 Do (will/would) you reuse/recycle the ID? (partly e.g. vacuum bags) 7. Synthesis Rank the properties that must have the mater of which is made the ID (1: mandatory 9: not necessary) 3 low attenuation levels (+homogenous) 7 lightweight 2 durable 7 cheap 1 efficient (less movement permitted) 9 reusable 5 modifiable during the treatment course 6 not claustrophobia/anxiety inducers/open or transparent 4 comfortable 2 Procedure description 2.1 General considerations Several issues, specific to the upcoming Particle Therapy Center of Marburg, had to be taken into consideration in the process of optimizing the patient immobilization concept. The PTZ will be equipped with robotic tables in the irradiation rooms (caves) and CT rooms. For patient immobilization, designated preparation rooms are planned. In the eventual Page 6 of 8

7 workflow, the patients will be moved between the preparation rooms, CT rooms and caves on a specially designed shuttle. The preparation rooms will be equipped with specially designed recliners with the help of which the couch top (together with a vacuum cushion) will be put to nearly vertical position (patient getting in the vacuum cushion) and lowered to horizontal position to be placed on the shuttle. The technical solutions regarding the patient couch at PTZ are provided by Siemens PT (Siemens, Erlangen, Germany), therefore the selected immobilization equipment had to be compatible with the robotic table provided by Siemens. Only flat table top solutions are possible (no pod, no stereotactic fixation system protruding beyond the edge of the table). 2.2 Immobilization concept outline for specific anatomical sites a) Head For irradiations of head tumors, 3-point thermoplastic masks of continuous (non-perforated) material (Aqaplast or equivalent) with individual mouthpiece to improve the reproducibility of immobilization, currently under tests in the clinical routine at the Department of Radiotherapy in Marburg, are planned. The mask will be moulded with special consideration to form precisely the chin, nasal ridge and eye brows. As additional equipment, a set of standardized or individual head supports will be used. For some irradiations and, in the future, for some (benign) ailments (like arteriovenous malformations or trigeminal neuralgia) considered as indications for particle therapy due to its high conformity, a table-top stereotactic immobilization system will be selected (enabling both, invasive and non-invasive fixation). b) Head-and-neck For irradiations of head-and-neck tumors, 5-point thermoplastic masks of continuous (nonperforated) material (Aqaplast or equivalent), currently under tests in the clinical routine at the Department of Radiotherapy in Marburg, will be used. The mask will be moulded with special consideration to form precisely the chin, nasal ridge and eye brows and to obtain reproducible placement of patients' shoulders. As additional equipment, a set of standardized or individual head supports will be used. Page 7 of 8

8 c) Pelvic region For treatments in the pelvic region the supine position with whole body vacuum cushion or pelvis mask is planned (tests on-going). During the practical feasibility tests, performed at the Department of Radiotherapy in Marburg by a multidisciplinary team of RTTs, medical doctors and physicists, guidelines were defined on forming the vacuum cushions in order to avoid introducing moulded material in the way of possible irradiation ports. In the start-up phase (before the introduction of the reclining device and the shuttle), shorter vacuum cushions encompassing only the area between tights and waist, easier to use for the patients, are considered. In prostate treatments the issue of internal target movement will be addressed by applying a bowel/bladder preparation protocol and dietary advice. The use of endorectal balloons (ERB), recommended by some particle therapy centers, both as an immobilization device and a way to reduce adverse dosimetric effects of the air present in the rectum, is currently being tested. d) Upper abdomen and thorax Based on the experience gathered with radiosurgical lung and liver treatments at the Department of Radiotherapy in Marburg, for treatments in the upper abdomen and thorax region the use of whole body vacuum cushions is planned, for some patients in combination with an abdominal compression device. Additionally, clinical concepts are under development to apply Breath-Hold or Jet- Ventilation techniques to alleviate the problem of the breathing induced movement. Page 8 of 8